The present invention relates to a data relay controller for relaying data to and from a buffer memory.
FIGS. 1 to 3 illustrate the logic format of data recorded on a known digital versatile disc (DVD). FIG. 1 shows the configuration of a data block to which an error correction code (ECC) is added. The data block includes information data, which is the desired recording information, such as dynamic image data or address information of divided data units. The data block also includes a first parity, which is applied to every predetermined piece of information data, and a second parity, which is applied to every predetermined amount of data including the information data and the first parity.
A data block includes 172×192 bytes of information data. The data block has 172 columns of data, each having a data length of 192 lines, in the vertical direction of the data block. An outer code parity (PO), which functions as the first parity and has a data length of 16 lines, is added to each column of data. Further, the data block has 192 rows (lines) of data, each having a data length of 172 bytes. An inner parity code (PI), which functions as the second parity and has a data length of 10 bytes, is added to each row of data and each line of the outer code parity.
FIG. 2 is a diagram illustrating an interleaved data block. The data block of FIG. 1 is interleaved and divided into 16 data sectors. Each data sector includes 12 lines of information data. Further, a line of the first parity is added to each data sector.
FIG. 3 illustrates the configuration of the data sector. The data sector includes 12 bytes of header data. The header data includes 4 bytes of identification data (ID), two bytes of identification error detection data (IED), and 6 bytes of copy management data (CPM). Further, the data sector includes 2,048 bytes of main data and four bytes of error detection code (EDC) data.
The data having such a format is temporarily stored in a dynamic random access memory (DRAM) of a DVD recording device or a DVD reproducing device.
In the data stored in the DRAM, only the main data is requested to be transferred to an external device. Further, only the main data is requested to be stored in the DRAM from the external device. When processing each request with a control unit that controls each process in the DVD recording device or the DVD reproducing device, the operation load applied to the control unit becomes large. This may drastically decrease the processing speed or cause deficiencies. To cope with such problems, an exclusive line for relaying data may be provided between the DVD recording device and reproducing device. However, this increases the circuit scale of the DVD recording device or reproducing device. Thus, the employment of such an exclusive circuit is not preferable.